1. Field of the Invention
The application relates to measuring a nip load profile and to a roll intended for measuring the profile. The roll can be used in a paper, board or tissue machine, in a press, calender, coating station, reeler, winder, printing press and the like. In addition to rolls needed in the process of plastic film manufacture and lamination, the measurement of a nip pressure profile provides benefits in chipboard lines, pulp sheet lines, in the production of various building boards, including concrete, plaster and ceramic boards. The nip can be for example between two or more rolls, between a tensioned belt and a roll or between a rigid board and a roll.
2. Description of Related Art
A nip is formed when a web or a bulk material in the form of sheets is pressed with a roll, a belt, a shoe or the like element. Thus, the nip may comprise a roll-pressing belt or two opposing rolls, and between the actual product to be manufactured or pressed and the pressing roll or other element may travel a felt or a wire or an imprint-delivering board or belt. Hence, the nip is not just a press zone between two rolls.
Documents dealing with the topic include at least EP642460 and EP517830. The latter proposes mounting a pressure sensor on a roll surface for measuring a nip pressure, but the practical equipment according to that application did not work too well.